1. Field of the Invention
This invention relates to a fluid-impermeable composite hose, and more particularly, to one for transporting a fluid, such as any of various kinds of gases, gasoline or a refrigerant. This invention is particularly useful as a hose for transporting a refrigerant, such as flons or carbon dioxide.
2. Description of the Related Art
As a hose for transporting a fluid, there is a demand for a fluid-impermeable hose which can, for example, transport any flon as a refrigerant without allowing it to leak out into the atmosphere and destroy the ozone layer, or realize a cooler system not necessitating any replenishment of a refrigerant, or a fuel hose not allowing any fuel vaporization. There is a particularly large demand for an improved hose for transporting e.g. carbon dioxide as a refrigerant, since this refrigerant gas easily permeates through the wall of a hose for a number of reasons including its high pressure, high temperature and low molecular weight.
It is effective to use a metallic foil to make a hose which is highly impermeable to a fluid and yet sufficiently flexible to resist any vibration satisfactorily. The foil has, however, the drawback of being broken very easily. Attempts have, therefore, been made to form a hose from a laminated sheet prepared by holding a metallic foil between a pair of resin films, or from such a laminated sheet and a thin elastic layer of e.g. rubber bonded thereto, so that the materials used with the foil may reduce or absorb the bending or expansive deformation of the hose which may cause the foil to be broken.
These attempts are effective for preventing the fatigue failure of the foil from being caused by its abnormal deformation, including wrinkling, as a result of the repeated bending or deformation of the hose, but there has not been proposed any hose including a metallic foil which is not broken by a tensile force when the wall of the hose is stretched.
A metallic foil forming a hose is not only broken when the hose is bent or deformed, but it is also broken easily when pulled, since it is hardly stretchable. If a hose formed from a laminated sheet comprising a metallic foil and resin films expands and has a wall portion stretched when holding a fluid having an elevated pressure, it is often the case that only the foil is broken, while the resin films remain unbroken because of their stretchability.